DD-WRT Transparent proxy configuration

dd-wrt-transparent-proxy.sh

#!/bin/sh
PROXIFYING_MACHINE=192.168.0.145
MACHINE_TO_PROXIFY=192.168.0.113

iptables -I PREROUTING 1 -t mangle -s $MACHINE_TO_PROXIFY ! -d `nvram get lan_ipaddr`/`nvram get lan_netmask` -p tcp -m multiport --dports 80,443 -j MARK --set-mark 3
iptables -I PREROUTING 2 -t mangle -s $MACHINE_TO_PROXIFY ! -d `nvram get lan_ipaddr`/`nvram get lan_netmask` -p tcp -m multiport --dports 80,443 -j CONNMARK --save-mark
iptables -I PREROUTING 3 -t mangle -s $MACHINE_TO_PROXIFY ! -d `nvram get wan_ipaddr` -p tcp -m multiport --dports 80,443 -j MARK --set-mark 3
iptables -I PREROUTING 4 -t mangle -s $MACHINE_TO_PROXIFY ! -d `nvram get wan_ipaddr` -p tcp -m multiport --dports 80,443 -j CONNMARK --save-mark

ip rule add fwmark 3 table 13
ip route add default via $PROXIFYING_MACHINE table 13